When a user logs into a website for an online content service, the user begins a browsing session in which the user's activities or events can be analyzed to determine such things as webpage navigation, session duration, internal referrals, and/or external referrals.
Some online content services encompass multiple websites. If a user visits a number of these websites after logging onto an online content service, the user's activities or events on a specific website can be analyzed as a subsession.
However, browsing sessions and subsessions do not lend themselves to granular analysis of user engagement with a specific item of content, such as a text article or video.